This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This O-GlcNAc posttranslational modification is highly dynamic and draws comparisons with protein phosphorylation as a biological control mechanism. It has been implicated in gene transcription, nuclear trafficking, protein translation, signal transduction, the regulation of protein-protein interactions, and the sensing of nutritional levels within the cell. Dysregulation of O-GlcNAc contributes to the aetiology of important human diseases, particularly diabetes and neurological disorders. Unlike phosphorylation for which a wide range of pan- and site-specific phospho-antibodies are available, studies of O-GlcNAc modification are hampered by a lack of effective tools for its detection, quantification, and site localization.